Effect Of Surface Texturing On The Friction And Lubrication Performance Of Sliding Guideway

The surface texturing technology is applied to the sliding guideway in order to solve the problems of high friction,easy wear,and poor low-speed stability of the traditional sliding guide pair.The fabrication,characterization and friction properties of the textured guide surfaces were studied.By studying the effect of texture on the surface topography distribution,contact deformation,oil supply and storage of the sliding guide,a roughness parameter set for textured surface characterization is developed for engineering applications.The tribological model of the textured rough surface was established.The effect of texture on the friction and wear performance of the surface was obtained,which provides a theoretical basis and guiding scheme for the development and application of the textured sliding guide.The mechanism of laser technology to prepare textured guide surface is studied,the preparation process of textured surface is established,and the optimal laser processing parameters are obtained:the groove is processed by the rectangular filling method with a scanning distance of 5 μm,and the laser power is 2-4 W,pulse time 10 ns,scanning frequency 290 kHz,scanning speed 2 mm/s,the corresponding micro-texture depth is about 1-10 μm,and the micro-texture width can be freely adjusted as needed.The morphological characteristics of the textured surface are studied,and a set of roughness parameters(Sq,Sbi*,Sci*and Svi*)suitable for the textured surface is proposed.Among them,Spq represents the roughness of the upper Gaussian surface,which can reflect the initial surface state before microtexturing,and this parameter plays a decisive role in the contact and friction of the surface;Sbi*,Sci*and Svi*reflect quantitative evaluation of functional properties in terms of peak,core,and valley volumes,respectively.These indices describe the effect of micro-texture on surface regions,reflecting their impact on surface contact,lubricant storage,and wear debris capture.Surfaces with different morphologies were designed and fabricated according to the initial roughness Sa of the surface before microtexturing and the depth d and density δ of the micro-texture.The effect of texture on the friction properties of the guideway surface under different lubrication conditions was studied using the pin-on-disk setup.The correlation between the roughness parameter group and the friction performance was analyzed.Under the immersion lubrication condition,the friction coefficient of all textured surfaces are larger than that of the untextured surface,and the increase of the friction coefficient grows with the increase of micro-texture depth and density;under limited lubrication conditions,texturing can reduce the friction coefficient of the surfaces.The decrease of the friction coefficient of the textured surface grows with the decrease of the initial roughness and decreases with the increase of the texture depth,but first increases and then decreases with the increase of the texture density.The optimal micro-texture design parameters are:depth of 1μm and density of 15%.The textured surfaces(TS)using these parameters reduce the friction coefficient by 15%-39%compared to the untextured surface(US).By conducting the correlation analysis between the roughness parameter group and the textured surface friction performance,it is found that the surface friction performance is mainly determined by Spq when the oil supply is sufficient,while Sci*has a great influence on the lubricating performance maintenance when the oil supply is insufficient.By constructing lubrication models under different lubrication states,the effects of texture on the contact deformation between surfaces,oil storage and oil supply,and dynamic pressure bearing capacity were studied,and the friction and lubrication mechanisms of textured surfaces were analyzed and discussed.When the oil supply is sufficient,under the boundary lubrication state,the texture will aggravate the surface deformation and increase the surface lubrication;in the full film lubrication state,when the oil film thickness is small,the micro-texture will impair the fluid carrying capacity of the rough surface,and the deeper the micro-texture depth or the greater the density,the greater the impact on the surface bearing capacity;in the mixed lubrication state,the texture will weaken the dynamic pressure on the surface,resulting in a decrease in the average oil film thickness and an increase in the contact deformation,the dynamic pressure bearing ratio decreases,and the surface friction coefficient increases.When the oil supply is insufficient,the micro-texture can increase the surface oil storage and oil supply capacity,reduce the contact friction,and enhance the local dynamic pressure bearing.Therefore,it is necessary to comprehensively consider these two factors in the texture design,and select the texture parameters reasonably.The guideway sliding test machine was designed and built,and the friction and wear and low-speed stability of the guideway under different loads and speeds were studied under the simulated actual working conditions of the sliding guide.The results show that compared with the pin-on-disk test,under the same load,speed and lubrication conditions,the friction coefficient of each guideway pairs in the platform test increases,which is closer to the boundary lubrication state.Under the same test conditions,the friction force,wear and low-speed creep amplitude of the upper textured guideway(UTS)and the both sides textured guideway(BTS)are all higher than those of the non-textured guideway(NTS).The increase is not conducive to the improvement of friction performance;while the performance of the lower textured guideway(LTS)in terms of friction,wear and low-speed stability has been enhanced,the friction force is reduced by about 12%on average,and the wear depth is reduced by 15%,the amplitude of friction fluctuation can be reduced by up to about 80%during low-speed crawling,and the low-speed stability is significantly improved.This is mainly because in the working environment of the general sliding guideway,the lubricating oil is mainly stored on the surface of the lower guideway,and the textured lower guideway surface can store more lubricating oil to ensure the oil supply of the contact surface,so it can improve its performance.However,the micro-texture on the surface of the upper guideway will aggravate the surface contact deformation and increase the contact stress,so it is not conducive to the improvement of the surface friction performance.